1. Field of the Invention
The present invention relates to binocular magnifying glasses which are worn for examining an object in a magnified manner when performing precision work by hand, etc.
2. Description of the Related Art
In conventional binocular magnifying glasses of this type, there has been known the technology disclosed in Japanese Examined Patent Publication (Kokoku) No. 2-38933. The binocular magnifying glasses described therein are comprised of a pair of magnifying optical systems, each consisting of an objective lens having a positive power and an eyepiece having a negative power arranged in that order from the object sides one system for each of the right and left eye. The distance between the objective lens and the eyepiece is adjustable depending on conditions of the wearer's eye and the distance of the object. Further, the distance between the optical centers of the objective lenses and the distance between the optical centers of the eyepieces could be independently adjusted.
In these binocular magnifying glasses, it is possible to adjust the position of the lenses so as to match the optical centers of the eyepieces and objective lenses with the line connecting the center of rotation of the wearer's eyeballs and the object each time worn. Since it is necessary to adjust four lenses independently in accordance with the distance between the eyes of the wearer, it is difficult to use these binocular magnifying glasses.
Further, to make the interobjective lens distance variable and match it with a wearer with the smallest conceivable interpupillary distance, it is necessary to make the diameters of the objective lenses relatively small to enable their being adjusted close together. This is one of the major restrictions in securing a broad field of vision in binocular magnifying glasses.
Further, the convergence of the eyes when using the binocular magnifying glasses is stronger than the convergence of the eyes without the binocular magnifying glasses and so it is difficult to obtain a balance between convergence and recommendation. The wearer is therefore not able to withstand long-term use.